Ignition system



July 15 1924. 1,501,484

J. H. Hum' IGNITION SYSTEM Filld SCPI. 3, 1918 2 ShlUlI-'shii l lijn/.l1

July 15 1924. 1,501,484

.1. H. Hum

IGNITION SYSTEM M i y/62%@ W4 Patented July 15,. 1924.

UNITED STATES PATENT OFFICE.

JOHN H. HUNT, OF DAYTON, OHIO, ASSIGNOR TO THE DAYTON ENGINEEING LABORATORIES COMPANY, A CORPORATION OF OHIO.

IGNITION SYSTEM.

pplication filed September 3. 1918. Serial No. 252,316.

To all whom t may concern:

Be it known that I, JOHN H. HUNT. a citizen of the United States of America. residing at Dayton, county of Montgomery,

n State of Ohio, have invented certain new and useful Improvements in Ignition Systems, of which the following is a full. clear, and exact description.

This invention relates to ignition systems` for internal combustion engines aild the like.

One of the objects of the invention is to provide an ignition system` including an ignition coil which is constructed in such a manner that the coil can be placed in the vicinity' of metallic bodies, such as the cast-iron cylinders of the engine, without substantially affecting the operation of the coil.

.Another object of the invention is to provide an ignition coil in which for a given ratio of secondary and primary turns the best ratio of transformation can be obtained.

A further object of the invention is to provide an ignition system including an ignition coil 1n which the inductance can be varied in accordance with the operation of the engine with which the system is employed.

More particularly it is an object to provide an ignition coil which while the engine is ruiming at a low speed will have a high inductance in order to obtain a hotY spark while the engine is starting or run-- ning' slowly. and devices for reducing the inductanoe of the coil at high engine speed in order to obtain a faster working coil, so that although a large number of sparks are required at high speed the eliiciency of the spark will be maintained at a maximum.

Other and further objects of the present invention will be apparent from the following description, reference being made 11o the accompanying drawings, in which certain embodiments ot the invention are shown,

In the drawings: e

Fig. 1 is a Wiring diagram of an ignition system embodying the present invention;

Fig. 2 is a wiring diagram of an ignition system embodying a modified form of the Fig. 4 is a side elevation partly in sec-i' tion of an ignition timer, including controlling devices forming a part of the present invention.

Referring to Fig. l, designates as a whole an ignition coil including a C-type core 11.Said core l1 includes main core portions 12 and 13 which are separated by a relatively narrow gap 14, and yoke portions 15 and 16 which are connected together by auX- iliary cores 17 and 18. The primary ignition Winding 20 is wound upon the main cores 12 and 13 and has one end thereofconnected by a wire 21 with an ignition switch 22 which is connected by wire 23 with a battery 24 which is grounded at 25. The other end of the primary winding 20 is connected by wire 26 witha timer 27 which is connected by wire 28 with a rheo-` stat resistor winding 29. A wiper 30 cooperates with the resistor 29 and is grounded at 31.

The secondary ignition winding 32 Wound around the main cores 12 and 13 and the primary Winding 20 and has one end thereof grounded through the battery by means of the wire 21, switch 22 and wire 23, and the other end thereof is connected by wire 33 with a distributor 34 which is connected with the various spark plugs 35 of the engine (not shown)` A. controlling Winding is mountedon the auxiliary core 17 and one end thereof is grounded at 41 and a controlling wind-- ingl 42 is mounted on the auxiliary core 13 and is grounded at 43. Both-windings 40 and 42 are connected in parallel with each other and both together in series with the Wire 44 which isv connected. with a rheostat resistor 45. The wiper 46 cooperates with the wiper 45 and said wiper 46 is connected by wire 47 with wire 21.

Tipers 30 and 46 may be mounted on the same lever, or, as shown in Fig. 4 may be separately mounted and may be moved together by the same actuating element.

"slot 5 7 and the straight a. `substantially 'tact members 71 and 7 2 Referring to l*`ig. 4, 5U designates as a whole a timer unit Whicl'l includes a housing 51 in which a shaft 52 is journallcd by means of bearings 53 and 54. 'Shaft 52 carries 'a gear 55 which meshes with thc gear 56, said gear 56 being connected with Vthe crank shaft of the engine by any suiti able means (not shown). The shaft 52 is of hollow construction and is provided with a spiral slot 57. A cam shaft 58 having a straight slot 59 is mounted within the upper end of the shaft 52. Sleeve 60, mounted to slide axially of the 'shaft 52. carries 4a pin 6l 'which passes diametrically across the sleeve and through the spiral slot 59. Said pin 61 serves as a driving connection between the shaft 52 and theshaft 58, and by reason of the cooperation of the pin 61 with the sliding sleeve in the members 52 and 58.1"liesliding moven'ientV of the said sleeve 60 7Will cause 'relative angular movement between the shaft 58 and the shaft 52. This movement' is effected automatically according to the speed of the engine by means of `member j62 which is pivoted at1'63 upon'they'shaft 52 and is connected by' a link 64 Withthe sleeve 60. lt is evidefn't'that as the speed of the shaft 52 increases the member 62 will tend to assume .Y horizontal .position and thereby cause fthe sleeve `6() to' move up wrdly to'cau'se the "displacement of member 58 relativelyz to the shaft 52. This movement 'of sleeve '60 due to centrifugal forceacting on 'the member 62 is resisted by,s ri'ng 6.5"interposed`betweensleeve 6() and lhe bearing 54. i,

LA cam s mounted on the shaft 58 and Serves'to effect the" engagement of timer conwhich are. included as elementsof 'the timer27. Upon 'the up per end of the shaft 58 is mounted a dis tributor rotor 73 which is shown dia ram inatically in' Fig. l as 'cooperating Wit sta tionarycontacts 74.

`The 'wipers 30 and 46 the frame 5l at S0 VViper 30 engages with the sleeve 60 where by the longitudinal movement of said sleeveI will cause a pivotal movement of the wiper 30. The movement of the Wiper 30 is trans` initt'ed to the Wiper 46 by means of the link '82.

The resistor 29 'is mounted upon a spool 83 which is mounted on a shaft 84 carried by the frame 51'. Spool 83 is provided with a crown tooth ratchet 85'vvhich cooperates with a payvl 86 carried by a lever 87 which isv mounted at 88 upon the frame 5l. The wiper 30 is provided with a lug 89 which upon the upward travel of the Wiper 30 strikes against the portion 90 ofV the lever 87 and causes the pawl 86 to move the ratchet 85 a `distance corresponding to' the space beare pivoted upon and 81 respectively.

tween adjacent ratchet teeth. The spring 91 cooperates with the teeth 65 to prevent the turning of the spool 85 in a reverse direction. The resistor 45 is mounted in the same fashion as the resistor 29. ticular mounting of the resistors 29 und 45 is not a part of the present invention but is described and claimed in the patent of Charles F. Kettering; and \'Villiam A. Chryst, No. 1,272,055 issued July 9, 1919.

It is evident Jfrom the foregoing descrip tion of the timer unit 50 that as the speed of the engine varies the position of the wip ers 30 and Li6 will vary in accordance there With. The construction and arrangement is i such that as the speed increases the wipers Will be actuated to cut resistance out of the circuits in which the resistors are included. The operation of the device shown in Fig. l, and the supposed underlying theory, is as follows: The ignition switch 22 is closed and the engine is started in the usual manner. When timer contacts 7l and 72 are closed current will build up in the primary winding 20, thereby creating a magnetic field in the vicinity ot' the windings 2O and 32. By making the magnetic circuit shaped 'with a very short air gap within the exciting Winding, the reluctance of the magnetic circuit is concentrated within the Windin thereby causing the energy of the coil to e stored in said air gap and within a small fringe about it. By carrying the density as `high as possible for the core iron used it is possible to store a large amount of energy in a comparatively small space.

Thus by storing the energy within the gap, -when this energy is released, the magneto-motiveforce'released will be expended within the coils 2O and 32. The magnetomotive force effective at. the ends of the coil 20 and 32 is reduced to a minimum, and therefore there is substantially no tendency for leakage to occur as inthe case of the conventional type coil (having a straight bar core around which the windings are placed). This characteristic of the type of coil disclosed embodying the present invention permits of'location close to metallic bodies which are magnetic, as the iron cylindersl of an internal combustion engine,` or non-maghetic as a brass base or housing for the coil. The conventional type coil does not permit of such location without seriously interfering with the operation therey of. An exploration of the field of the conventional type coil would show that most of the energy of the coil is concentrated close to the ends of the core. The introduction of any masses ot metal in this region would cause trouble. lt iron is intro duced, the field will be distorted and there will be a possibility that the inductance of the coil will be greatly increased. If the inductance is increased and the coil is any- The parthing like an economical construction, the core will become saturated before the usual maximum current is reached. As a result of the high inductance at low currents under high speed running conditions, the current will be held down to a smaller value than would otherwise be reached, while at lower speeds there will be no more energy in the coil than if the masses of iron were not there. Since practically the total inagneto-motive force of the primary is effective at the ends of the primary core, the tendency of leakage flux through the masses of iron in the vicinity is very high. If, on the other hand, instead of iron there is brass in the field, the field will not be distorted, but owing to a comparatively low resistance of the metal. eddy currents will be set up in the metal at the time of the break of the primary ignition circuit, and practically all of the energy represented by this part of the flux will be lost. But in the type of coil disclosed embodying the present inven` tion, none of the foregoing disadvantages of the conventional type coil are present.

lt is obvious that if the iron of the external magnetic circuit of `the type of coil disclosed could be removed during the op eration of the coil, it would be possible to reduce the inductance of the coil very materially. If this iron of the external circuit can be saturated so thoroughly that it can not carry any of the ignition coil flux the effect will be practically the saine as if the iron were removed. It is, of course, esselr tial that this saturation of the magnetic circuit be carried out in such a Way that there are no windings about any part of the magnetic circuit which can act as short circuits with respect to the voltage induced by the flux change caused by the break of the cu1 rent in the primary.

This result is accomplished in the following manner.

Then the engine is running slowly, all the resistor windings 45 are in circuit and very little current will fiow to the windings 40 and 42. As the engine speed increases wiper 46 will be automatically moved to cut out resistance and to permit an increasing amount of current to flow through said windings 40 and 42. It will be .noted that the magnetic circuit is completed through the yokes 15 and 16, and the auxiliary cores 1T and 18 act in parallel as far as the flux due to the primary is concerned. Since the change of flux due to the winding 20 Tvill Vbe substantially the saine in cores 17 and 18` and since the windings 4l) and 42 have an equal number of turns and are connected as shown in Fig. 1. the electromotive forces genera-ted in said windings 40 and 42 by the pulsations of the main flux will be opposed. and will be substantially balanced, and substantially no current will be induced in the windings 40 and 42. With the windings 4() and 42 thus arranged, a direct current sent through them tends to send flux around cores 17 and 18 and the end yokes Without directly affecting the magnetic or electricl circuit as at the left of the line A-A.

By reason of the ability of regulating the inductauce of the type of coil disclosed in the manner described, an ignition system including said coil possesses certain advantages over the system using the conventional type coil. The coil can be constructed so as to have the minimum inductancc available when the coils 40 and 42 are fully excited, said inductance being of the proper value for the highest speed Work that is required of the coil. At low engine speeds the coil can be run without any excitation in the regulating coils 4() and 42 with a result that, the inductance being higher, the ignition coil. produces a hotter spark for starting or for low speed runningr conditions. Vhere the inductance of a coil cannot be varied according to the speed of the engine construction of the coil is restricted between certain limits. The limit on one hand is the inductance required at starting but which would be too high lfor high speed conditions; and the limit on the other hand is the inductance required at high speed which would be far too low to obtain a hot spark at starting or slow speed conditions'. The inductance of the coil of the conventional type is. somewhere between these limits-but cannot be the ideal value for all engine speeds. But with the type o1' coil disclosed it is possibleto reduce the inductance 30% o the'initial value, permitting the inductance for slow speed Work to be over 40% greater than would be otherwise possible where the inductan'ce could not be varied,v land, at the same time, proriding for ignition required for highest speeds. It was found by experiment that the striking distance of the spark at high speeds was better in case of type of coil disclosed than the conventional type, when operated at the. same speed.v

It is not essential that the current through the primary winding be regulated in accordance with the speed of the engine, but Where the connections are as shown in Fig. 1 it may be desirable to do so in order thata certain proportion between the current passing through the Winding 20 and current passing through the windings 40 and 42 may be maintained at certain speeds. It is not essential that the windings 40 and 42 be connected in parallel but it has been found that this connection is preferable.

The control of the current passingr through the windings 4U and 42 may be effected inv other Ways than in the manner shown in Fig, 1 and already described. The

regulating current passing through windings-40 and v-42 may be switched on only when high speed is reached by a 4manually controlled switch located somewhere in the connections between the battery and the windings, or the switch may be controlled h r a centrifugal governor. Another Way in which the windings 40 and 42 ma be controlled is shown in the modified orm ofthe invention shownin Fi .'2.

Referring to Fig. 2, 100 re ers as ,a whole to a shunt fieldthird brush regulatinggenerator having an armature 101, brushes 102, 103and 104, and field wind-ings 105 and 106. The positive brush 102 of the generator 100 is connected with the reverse current relay 107 which is connected by wire 108 :with the wire l23 connected with the battery 24. The negative brush 103 of the generator 100 is grounded at 109 thereby effecting a connection'with thenegative side ofthe battery through the ground 25. The larmature 101 is rotated in the direction of-thearrow 110. The shunt windings 105 and 106 are connected between the third brush 104 and lthe brush 102. .The third brush is connected-by wire 44 with the windings 40 and 42 which are grounded at 41 and 43 respectively. When the enerator is operated, the third brush 104 eing at a higher potential than the brush 103, current will How through the wire 44-and the windings 40 and 42 to ground connection 41 and 43 respectively and hack through nground 109 to the brush 103. When lthe generator is running slowly with 'slowengine speeds, the potential difference between brush 104 and brush 103 will be very small, consequently the windings 40 and 42 will have very little regulating effect. As the speed of the generator increases with increased engine speed the4 field v will be distorteddue to armature reaction with a result that vthe otential difference between brushes 104 and) 103 will be materially increased. This regulatinggeifect is taken advantage of in previous devices. to reduce the battery charging rate of high speeds. since the output of thegenerator is reduced with the reduction of `iield excitation at high speeds. But while the 4field excitation is reduced due to the drop in potential between brushes 102 and 104, the potential between 104 and 103 will increase with increased engine speed and this characteristic can be taken advantage of tocausean increased amount of current `to vflo-w through the windings 40 and 42. It has been found that an 'ignition systemY embodying the type of coil described in combination wlth a third brush regulating generator Willhave very satisfactory characteristics. Thus the desired effect obtained by regulating the inductance according to speed can beproduced automatically through the agency of a third brush regulating generator which is generally'employed in theelectrical equipment of an automoblieengine.

Referring to Fig. 3 in which a modified form of the ignition coil is shown, 120 indi cales as a whole the fore including innin cores 121 and 122, ),'okcs 121 and 124 and auxiliary cores 1.25 and 120. The cross scc tional areas of cores 125 and 126 and yolres 123 and 124 are equal, and each is equal to one#half the cross sectional area Ji the main cores 121-and 122. -The primary winding 20 and the secondary winding 32 are wound around the main cores 121`and 122, and the connections between these windings, distributor, timer and battery are the saine as shown findig. 1. The regulating windings and -126 respectively. The winding -40 is grounded at `41 -and the winding 42 is grounded at 43 as 'is the case of the system 5 shown in Fig. 1. The-wire `44connecting this wire inparal-lel may-be connected with the -rheostat'35 or-with the third brush 104. Theoperation of these coils is substantially the saine asthecoils shown in Figs. 1 and 2 but -it has been found that the characteristics ofthe coil shown in Fig; 3 may be better for some purposes than the characteristics of the coil shown in `Figs. "1 and 2. This may be due-to the fact that the end yokes 123 and 124 maybe entirely saturated by the regnlating windings .4 0 and v42 while in the case of the coresshown in Figs. 1 and 2 that poi'- tion f the cores to the left of the line A-A cannot besaturatedby-the windings 40 and 42. The following --dimensions of the core and windings are-given for purpose of illustration-only, and it is to be understood that the invention is not restricted to these dimensions or to the exact proportions between them. The primary winding 20 may have 250 turns of number 21 wire, the secondary winding 20 12,500 turns of No. 36 wire, and the windings 30 and 32 each may have 1,125 turns of No.23-wire. The main core cross sectional area is .500 square inch and the sectional area of the yokes 123 and 124 of 'the cores 125 and 126 is .125 square inch. The outside dimensions of the cores are 3.175 inches by 4.125 inches by .500 inch. The coil having these dimensions was found to have an inductance of substantially 10 millihenries at low s eed and that the inductance could be re uced to (i millihenries at high speed. It was found by experiment that the coil just described has a better steady7 striking distance at hi h speeds than a coi having a core of the s ape shown in Fig. 1 and having slightly less copper and more iron, and a better steady striking distance at high speeds than a. coil of the conventional type which was constructed to furnish ignition .under the same conditions. It was Around that thecharacteristics of the coil shown in Fig. 3 having the dimensions referred to are very satisfactory at low speeds as well as liigh speeds.

iVhile the forms of mechanisms herein shown and described constitute preferred forms of embodiments of the invention` it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow:

1. In an ignition system, the combination with a source of current', and sparking devices: of :in ignition coil including wind ings adapted to he connected with the. source and sparking devices, and including a core; and provisions for changing the inductance of the coil by varying the reluctance of the `material of the core.

2. In an ignition system 'for internal combustion engines, the combination with a source of current and sparking devices; of an ignition coil having a C-type core with a fixed gap: and engine operated means for varying the reluctance of the core in rev spense to variations in engine operation.

3. In an ignition system for internal combustion engines, the combination with a Asource of current and sparking devices; of an'ignition coil including a core and windings adapted to be connected with the source and sparking devices; and means acting automatically in accordance'with the operation "of'theengine forlsaturati'ng a portion of the core whereby coil. 1 4. In iin-ignition System for internal combustion engines, the combination with a source of current and sparking devices; of an ignition coil including a core and windings adapted to be connected with the source and the sparking devices; auxiliary iwindings cooperating with the core for saturat ing a ortion thereof; and means acting automatically in accordance with the operation of the engine for varying the amont of current iowing through the auxiliary windings.

5. In an ignition system for internal combustion engines, the combination with a source of current and sparking devices; of an ignition coil including a core and windings adapted to be connected with the source and sparking devices: auxiliary windings cooperating with the core for saturating a portion thereof; a rheostat connected with the auxiliary windings and the current source; and means controlled by the speed of the engine for actuating the rheostat wiper.

6. Inan ignition system for internal combustion engines, the combination with a source of current and an ignition timer.; of an ignition coil including a core and windings adapted to be connected with the source and ignition timer; auxiliary windings cooperating with the core for saturating a portion thereof; and an engine operated device for controlling the timer and for controlling to vary the inductanceV of the the current pzissinr through the auxiliary windings, in accor ance with the speed of the engine.

i. In an ignition system for internal com liustion engines, the combination with a :cnr-'5c of current and an ignition timer; of an ignition coil including a core and main windings adapted to be connected with the source and ignition timer; auxiliary windings cooperating with theV core foi' saturating a portion thereof; and an engine o erated device for controlling the timer and or controlling tlie current. passing through the auxiliary windings, and for controlling the current passingr through the main windings.

8. In an ignition system for internal combustion engines, the combination with a source of current and an ignition timer; of

the timer and for varying the inductance- 0h95 the coil andv for'varyingfthe exciting current of the coil 10. In an ignitionsystem `for Iinternal combustion engines, the combination with a source of current and sparking devices of an ignition coil including main windingscooperatin with the source 'and sparking devices an a core-includin a, main core portion cooperating-` with e main windings p' and auxiliarycore 4portions of equal 'mag-:i105

netic `dimensionsffarrangalini-parallel `with each other and both together in series in the magnetic circuit containing the main core portion; auxiliary windings cooperating with the auxiliary cores; and means for automatically controlling the passage of current through the auxiliary windings in accordance with the operation of the engine. 11. In an i nition system, the combination with a uni irectional continuous .current source, and sparking devices; of an ignition coil including windings adapted to be connected with the. source and sparking-devices, and including a core; auxiliary windings cooperating with said core and connected to said source; and means for vary ing the current fiowing through said auxiliary windings to vary the reluctdnce of said core.

l2. In an ignition system, the combination with a source of current and sparking devices; o an ignition coil including a core, and exciting windings adapted to be connec-ted with the source and sparking devices; and means for varying the degree. of saturation of a portion of the core whereby to vary` the reluctance of the material of said core.

i3. In an ignition :system` the combination with a source of current and sparking devices: of an ignition coil including a core and exciting windings adapted to be connected with the source and the sparking devices; auxiliary windings cooperating with the core for saturating a portion thereof: and means for varying the amount of current flowing through the auxiliary windings whereby to vary the reluctance of the material of said core.

14. In an ignition system for internalcombustion engines, the combination with a current source and a timer; of an ignition coil including a core and exciting windings adapted to be connected with said source and said timer; auxiliary windings cooperating with said core for saturating a portion thereof; and means for controlling the timer and for varying the current in said auxiliary windings.

15. In an ignition system for internalcombustion engines, the combination with a current source and a timer; of an ignition coil including a core and exciting windings adapted to be connected with said source and said timer: and means forvarying the degree of saturation of a portion of said core and for controlling the ignition timer.

' 16. In an ignition system'orinternal combustion engines, the combination with a source of current and an ignition timer; of' an ignition coil having a C-type core with a fixed gap; and means for simultaneously varying the reluctance of the core and-for controlling the ignition timer.

17. In an ignition system for internalcombustion engines, the combination with a current source and a timer; of an ignition coil including a core and exciting windings adapted to be connected with said source and said timer; and means for varying the inductance of the coil, for controlling the current passing through the exciting windings and for controlling the ignition timer.

18. In an ignition system for internal-coinhustion engines, the combination with a current source and a timer; of an ignition coil including a core and exciting windings adapted to be connected with said source and said timer; and means varying the inductance of the coil and for controlling the .current passing through the exciting w-indings.

19. In an ignition system for internalcombustion engines, the combination with a current source and a timer; of an ignition coil including a core and exciting windings adapted to be connected with said source and said timer; auxiliary windings cooperating with said core 'or saturating a portion thereof; and means for varying the current passing through said exciting windings and for .varying the current in said auxiliary Windings.

20. In an ignition system for internaloombustion engines, the combination with a Vcurrent'so'urcez and a timer; of an ignition coil including a core and exciting windings adapted to be' connected with said source and said timer; auxiliary windings cooperating with saidcore for saturatin a portion thereof; and means for control ing the ignition timer, for Varying the current passing through'said exciting windings and for varying the current in said auxiliary windings. AIn testimony whereof I afiix my signature.

JOHN H. HUNT. Witnesses:

J. W. MCDONALD; M. A. PEASE. 

